Vapor-generating device



Aug. 23, 1966 N. CAMP 3,267,678

. VAPOR-GENERATING DEVICE Filed May 6, 1964 Y' 2 Sheets-Sheet l Y hotwater cold water N AT C AMP INVENTOR.

AGENT Aug. 23, 1966 N. cAMP i 3,267,678

VAPOR-GENERATING DEVI CE Filed May 6, 1964 2 Sheets-Sheet 2 NAT CAMPNVENTOR.

AGENI p 3,267,678 1Ce Patented August 23, 1966 3,267,678VAPOR-GENERATING DEVICE Nat Camp, 1316 Langdon Lane, Mamaroneck, N.Y.Filed May 6, 1964, Ser. No. 370,750 7 Claims. (Cl. 1 -108) Thisapplication is a continuation-in-part of my copending application Ser.No. 94,611, iled March 9, 1961 and now abandoned.

My present invention relates to a vapor-generating device adapted to beused for the dispensing of various substances in vapor form, for'humidication of the atmosphere of a room or the like, for distillationof sea water and other uids, for the operation of apparatus using vaporpressure as a source of motive power, and for related purposes.

A principal object of this invention is to provide a vapor generatoradapted to operate in a highly economical and efficient manner byconcentrating the output of an available heat source on a relativelysmall volume of liquid (generally water) to be vaporized.

A more particular object is to provide a source of lowpressure steamoperating on a very limited caloric input and with a short warmupperiod.

Another specific object of the instant invention is to provide aportable steam generator capa-ble of being incorporated, for example, ina compact unit immersible in a large body of water in such manner as tovaporize -only a small fraction thereof at a time.

It is also an object of this linvention to provide effective means forboth thermally and hydrostatically isolating a steam generator from arelatively large body of water from which this generator is continuouslysupplied.

4I have found, in accordance with the present invention, that the aboveobjects can be realized through the use of one or more capillary tubesinserted in a uid path between a relatively large body of liquid,specically water, and a relatively small boiler chamber, the capillarytube or tubes serving the dual purpose of regulating the influx ofliquid to the boiler chamber and preventing any backflow of hot water orsteam from that chamber to the yreservoir which, of course, wouldconstitute a loss of thermal energy. More particularly, I utilize thecapillary tube or tubes as a means for creating a hydrostatic pressuredifferential Ap of such magnitude that a given input pressure p, issubstantially balanced by the sum of Ap and a predetermined outputpressure po, the latter term being represented at least in part by thehydrostatic head in the boiling chamber which is therefore maintainedfilled with water to a substantially constant level.

The insertion of a capillary tube between the reservoir and the boilerchamber, in accordance with my invention, thus establishes therelationship:

so that, for example, a partially filled boiling chamber may be disposedsubstantially below the level of its water supply if both the reservoirand the boiling chamber are substantially unrestrictedly open toward theatmosphere, as in the-case of a vaporizer. If, on the other hand, thesteam generated in the boiling chamber is to drive a useful load, e.g. aturbine, a steam pressure equal to the load reaction will build up inthe boiling chamber and will be superimposed on the hydrostatic headthereof to constitute the output pressure p0. In order to provide acommensurately increased input pressure p1, I may constitute the supplyreservoir as a closed vessel whose internal pressure is'increased by theadmission of highpressure uid, e.g. water or air delivered by a pump orcompressor. Advantageously, in order to prevent a drainying of theboiling chamber toward the reservoir upon partial or complete failure ofthe input pressure (eg.

stoppage of the pump or compressor in the arrangement just described),the capillary tube or tubes should be so designed that po Ap.

As the cross-sectional area of the capillary tube is essentiallydetermined by the viscosity of the liquid employed, little variation inthat cross-sectional area is possible for the purpose of varying therate of flow therethrough. To maintain a desired ow rate it will,therefore, often be convenient to connect two or more capillaries inparallel; this mode of connection does not materially alter themagnitude of the existing pressure drop which in the case of each tubeis proportional to its length.

The boiling chamber may be designed in a variety of ways. Asubstantially cylindrical boiling chamber, horizontally disposed, hasthe advantage that a relatively small drop in liquid level will resultin a relatively large decrease of the surface of the water bath and,therefore, in a commensurate reduction in the back pressure of thedeveloping steam, if the latter is allowed to escape only through a.restricted outlet and/or by way of a load, once the bath level in theboiling chamber has fallen below its horizontal median plane. With anupright boiling chamber, on the other hand, an excess of rate ofvaporization over rate of supply will result in a more rapid decrease ofhydrostatic pressure in that chamber so that equilibrium will be morep-romptly restored independently of steam. pressure.

The heating of the boiling chamber may be effected lby various meansdisposed either within that chamber or externally thereof, an electricalheating element within the chamber being particularly advantageous inthe case of immersible or other compact steam generators.

The invention and its advantages will be better understood from thefollowing detailed description of certain embodiments, reference beingmade to the accompanying drawing in which:

FIG. l is an elevational view, partly in section, of a water tankequipped with a steam generator according to my invention;

FIG. 2 is a sectional view, on a larger scale, of the boiling chamber ofthe steam generator shown in FIG. 1;

FIG. 3 is an elevational view of a modified steam generator similar tothe one illustrated in FIGS. 1 and 2 but designed as an immersible unit;and

FIG. 4 is a diagrammatic view, partly in section of still anotherembodiment.

In FIG. 1 I have illustrated a tank 10 supported on legs 11 and filledwith water to a level 12. The bottom of the tank is formed with a drain13 overlain by a strainer 14 to prevent any :clogging thereof byentrained solids. Drain 13 merges into a capillary tube 15, with aninner diameter of one or two millimeters, terminating at the undersideof a cylindrical boiling chamber 16. The chamber is closed at one end bya cap 17 through which pass a pair of wires 18 for connecting a heater19 (FIG. 2) in its interior to a source of electric current. Charnber 16is also provided with a discharge tube 20 for generated steam, risingfrom its upper surface, and with a return pipe 21 for hot condensate,entering it from below.

A small sealed container 22, serving as a water separator, is shownsuspended by the conduits 20, 21 within tank 10 above the liquid level12. Tube 20 enters the container 22 from above to let any entrained onrecondensed water ilow back at its bottom into the pipe 21. An outlettube 23 for the nearly dry vapor extends upwardly from container 22 to avessel 24 serving for the storage of a volatile substance 25, e.g. aninhalant to be entrained into the atmosphere by the vapor passingthrough an extension 26 of tube 23 terminating in an upwardly openthimble 27 having a depending spout for the return of any residual waterto the tank 10.

The interior of chamber 16, visible in FIG. 2, also contains athermostatic switch 28 connected in series with the resistance elementof heater 19 acrossthe wires 18 to prevent overheating of the device.When switch 28 has been tripped open by an excessive rise intemperature, it may be manually reset by a button 29 after water hasagain been admitted to the boiling chamber. The discharge end of inlettube 15 is shown provided with a shutoff valve 311 to stop the influx ofwater into the chamber 16 during periods of non-use, thereby reducingthe time needed to start the gener-ation of steam when the device is putinto operation.

In use, wires 1S are plugged into an electric outlet to energize theelement 19 which heats the water in chamber 16. As steam begins todevelop, it expels from tube 20 any water that may have risen thereinand discharges it into container 22 whence it is returned to chamber 16via pipe 21. The steam then passes out through thimble 27, entrainingthe substance 25 in vessel 24. Fresh water enters the chamber 16 throughcapillary 15 at a relatively slow rate which matches the rate ofvaporization only after the pressure in the -chamber has droppedsuiiiciently to accelerate the travel of the liquid through this tube.As a result, steam will evolve rapidly enough to dissipate the heat ofelement 19 at temperature close to the boiling point of water atatmospheric pressure. I have observed, for example, that a boilingchamber of 22 mm. inner diameter and liO cm. length, heated by a250-watt element and supplied with water at 15 C. through a capillary of1.5

mm. diameter and 33 cm. length, began to generate water at anappreciable rate only two or three minutes after the heater had beenenergized. The length of tube 15, While not critical, should besuliicient to afford thermal insulation between the boiling chamber 16and the tank 10,

' in addition to providing the flow-retarding action necessary toprevent the escape of steam through drain 13 into the tank. The conduits20 and 21, whose inner diameters and cross-sectional areas should ofcourse be considerably larger than those of tube 15, could, if properlyinsulated to minimize heat losses, also be led through the interior ofthe tank, in the general manner illustrated in FIG. 3. Thirnble 27,which acts as a secondary liquid separator, may be omitted or replacedby some other outlet termination, if the device is to be used forpurposes other than room humidification and the entrainment of smallquantities of water by the steam is not objectionable.

In FIG. 3 I show a modified system generally similar to that describedin connection with the preceding figures and comprising a tank filledwith water; a unit 31, removably immersed therein, consists essentiallyof a boiling chamber 16' with thermally insulated walls and an insulatedjacket 32 rising from this chamber to a height above the Water level 12.The jacket 32 contains the conduits 20', 21 along with the liquidseparator 22 and a portion of the supply conductors 18". Outlet tube23', extending upwardly from -container 22, again directs the developingsteam through a vessel 24 for the purpose described in connection withFIG. 1; its extension 26 terminates in a thimble 27. An insulatingsleeve 33 partly envelopes the tube Chamber 16', Whose internalconstruction is similar to v that of chamber 16 shown in FIG. 2 andwhich is also of operation, i.e. while the boiling chamber 16 or 16'` issubstantially iilled and has not yet reached its state ofv equilibrium.Thus, either or both of these receptacles may be omitted in manyinstances.

In the embodiment shown in FIG. 4 a sealed storage tank 40 is providedwith an air compressor 41 in a duct 51 and a water-inlet pipe 42normally closed by a valve 50. The tank 4t) communicates with a somewhatsmaller boiler 46 by means of a plurality of coiled capillary tubes 45,extending from the lower part of reservoir 40 `to the lower part ofboiler 46. y

A source of Vheat shown diagrammatically as a gas heater 49, located at'the base of boiler 46, is provided for the heating lof its contents.

The boiler 46 also communicates with a steam turbine 44 by means of aconduit 43. A pipe 47 leading from the turbine 44 to the atmosphere actsas an escape ductor therused steam. Thermal insulation 52 surrounds thewall of boiler 46.

In operation, water is introduced into the reservoir 40 via the inletpipe 42 to the descent level whereupon the valve 5t) is closed.Thereupon, compressor 41 and heater 49 are actuated. Water from thereservoir 40 enters the boiler 46 through the capillary tubes 45 underthe combined pressure of air from compressor 41 and the hydrostatic headin vessel 40, this combined pressure being balanced by the sum of thehydrostatic head in boiling chamber 46, the steam pressure in thatchamber and the pressure drop across the three parallel-connected tubes45. Because of the small size of the boiler 46, the water entering it israpidly heated to produce steam which is piped through conduit 43 to theturbine 44, the steam driving the turbine 44 and being then releasedthrough the outlet pipe 47. Y

The system shown in FIG. 4 is intended for intermittentl operation ofthe turbine 44, with periodic replenishment of the contents of reservoir40 to maintain the Water level thereof nearly constant. Under thesecircumstances the Water level in boiling chamber 46 will also besufbjec't to but little fluctuation if the back pressure of the turbineis regarded as substantially constant. The tubes 45 constitute arestricted passage of predetermined hydrostatic resistance, and theprinciple `of operation will be substantially the same as in theaforedescribed instances. desirable to establish such a relationshipbetween the various pressure components referred to above that asubstantial amount of liquid is chamber 46.

For sustained operation, the system of FIG. 4 could be readily modiiiedto admit water continuously under suitable pressure, with use of -afeeding pump or a pressureregulated water supply, if necessary, throughpipe 42 so as to maintain the tank 40 always iilled to the top, lthecompressor 41 being then replaced by an airtight seal for duct 51.

As will be apparent from the preceding explanation of the principlesunderlying my invention, the embodiments described hereinabove may bemoditied in various ways, e.g. by a substitution of a boiling c'hamberas shown in FIG. 2 for the boiler 46 of FIG. 4 or by utilization ofdifferent types of heating means. My invention is, accordingly, notlimited to the specific arrangements herein disclosed but is capable ofnumerous variations and adaptations without departing from the spiritand scope of the appended cla-ims.

I claim:

1. A vaporagenerating device comprising a boiling chamber, a reservoircontaining a body of liquid substantially larger than the volume of saidchamber, said body of liquid being under a substantially constantdownward pressure of an overlying body of air, capillary-tube meansforming a restricted passage of predetermined hydrostatic resistancebetween said reservoir and said chamber, and heating means for boiling aliquid in said chamber, said capillary-tube means being so dimens-ionedas to develop thereacross an appreciable pressure differential Apmaintaining the liquid in said chamber at a substantially constant levelwith development of a substantially constant It is present at all time-sin boiling output pressure po at the chamber end of said capillarytubemeans in the presence of a substantially constant input pressure pi atthe reservoir end of said capillarytube means, with PiPo-l-Ap.

2. A vapor-generating device as `defined in claim 1 wherein saidreservoir is open toward the atmosphere, said boiling Chamber beingentirely disposed below the level of said body of liquid.

3. A vapor-generating device as defined in claim 1, further comprisingturbine means connected to said boiling chamber for operation by vapordeveloped therein, and a source of pressure lluid connected to saidreservoir.

4. A vapor-generating device as `defined in claim 1 wherein saidcapillary tube means comprises a plurality of capillary tubes connectedin parallel.

5. A vapor-generating device comprising, in combination with an upwardlyopen vessel containing a relatively large body of Water, a boilingchamber of relatively small volume disposed below the level of said bodyof water; a capillary inlet tube entering said chamber substantially atits bottom and opening into said body of Water, said reservoir beingclosed at its (bottom except for the inlet of said capillary tube; anoutlet tube of substantially larger cross-sectional area than said inlettube extending into the atmosphere from a location near the top of saidchamber but below said level; and heating means at said chamber forboiling water admitted to said chamber from said vessel by way of saidinlet tube, the latter being suficiently restricted to retard the.influx of water into said chamber upon operation of said heating meansso that said influx matches the rate of evaporation of Water from saidchamber in a partly lilled condition thereof whereby the water level insaid chamber lies below the level of said body of water despite equalatmospheric pressures upon said lbody of water through the open top ofsaid vessel and upon the Water in said chamber through said outlet tube.

6. A vapor-generating device comprising, in combination with a vesselcontaining a relatively large body of water, an elongated boilingchamber of relatively small volume disposed substantially 'horizontallybelow the level of said body of Water; a capillary inlet tube enteringsaid chamber substantially `at its bottom and opening into said body ofwater; an outlet tube of substantially larger cross-sectional area thansaid inlet tube extending into the atmosphere from a location near thetop of said chamber but below said level; and an elongated heatingelement extending in axial Adirection in `said chamber along the bottomthereof for boiling water admitted to said chamber from said vessel byway of said inlet tube, the latter being suiciently restricted to retardthe influx of water into said chamber upon operation of said heatingelement so that said influx matches the rate of evaporation of waterfrom said chamber only in a partly lled condition of said chamber.

7. A vapor-generating device comprising, in combination with anopen-topped reservoir containing a relatively large body oli-water, anelongated, `substantially cylindrical and horizontal boiling chamber ofrelatively small volume disposed entirely below the level of said bodyof water; a capillary inlet tube having one end connected to saidchamber substantially at its lbottom `and having another end connectedto said reservoir adjacent the bottom thereof; an outlet tube ofsubstantially larger cross-sectional area than sa-id capillary inlet`tube extending into the atmosphere from `a location near t'he top ofthe chamber but below said level; and an elongated electrical heatingelement extending in axial direction in said chamber along the bottomthereof for boiling water admitted to said chamber from said vessel byWay of said inlet tube, the latter being suiciently restricted to retardthe influx of water into said chamber upon operation of said heatingelement so that said influx matches the rate of evaporation of waterfrom said chamber only in a partly lled condition of said chamber.

References Cited by the Examiner UNITED STATES PATENTS 2,280,894 4/ 1942Cushman 122-27 X 2,453,455 11/1948 Persak 21-119 3,006,147 10/1961 Geary60-108 X MARTIN P. SCHWADRON, Primary Examiner.

ROBERT R. BUNEVICH, SAMUEL LEVINE,

Assistant Examiners.

1. A VAPOR-GENERATING DEVICE COMPRISING A BOILING CHAMBER, A RESERVOIRCONTAINING A BODY OF LIQUID SUBSTANTIALLY LARGER THAN THE VOLUME OF SAIDCHAMBER, SAID BODY OF LIQUID BEING UNDER A SUBSTANTIALLY CONSTANTDOWNWARD PRESSURE OF AN OVERLYING BODY OF AIR, CAPILLARY-TUBE MEANSFORMING A RESTRICTED PASSAGE OF PREDETERMINED HYDROSTATIC RESISTANCEBETWEEN SAID RESERVOIR AND SAID CHAMBER, AND HEATING MEANS FOR BOILING ALIQUID IN SAID CHAMBER, SAID CAPILLARY-TUBE MEANS BEING SO DIMENSIONEDAS TO DEVELOP THEREACROSS AN APPRECIABLE PRESSURE DIFFERENTIAL $PMAINTAINING THE LIQUID IN SAID CHAMBER AT A SUBSTANTIALLY CONSTANT LEVELWITH DEVELOPMENT OF A SUBSTANTIALLY CONSTANT OUTPUT PRESSURE PO AT THECHAMBER END OF SAID CAPILLARYTUBE MEANS IN THE PRESENCE OF ASUBSTANTIALLY CONSTANT INPUT PRESSURE PI AT THE RESERVOIR END OF SAIDCAPILLARYTUBE MEANS, WITH PI$PO+$P.